Motor fuel composition

ABSTRACT

MOTOR FUEL COMPOSITION COMPRISING A MIXTURE OF HYDROCARBONS IN THE GASOLINE BOILING RANGE CONTAINING (A) FROM 0.0004 TO 0.1 WEIGHT PERCENT BASED ON SAID COMPOSITION OF AN N-POLYAMINE SUBSTITUTED ALKENYL SUCCINAMIC ACID OR CORRESPONDING SUCCINIMIDE IN COMBINATION WITH (B) FROM 0.003 TO 0.20 VOLUME PERCENT OF (1) A POLYMER OF A C2 TO C6 UNSATURATED HYDROCARBON, (2) A COPOLYMER OF A C2 TO C6 UNSATURATED HYDROCARBON, OR (3) THE CORRESPONDING HYDROGENATED POLYMER OR COPOLYMER, SAID POLYMER OR COPOLYMER HAVING A MOLECULAR WEIGHT IN THE RANGE FROM ABOUT 500 TO 3500 AND A METHOD FOR OPERATING AN INTERNAL COMBUSTION GASOLINE ENGINE.

United States Patent Int. Cl. C101 1/18, 1/22 US. C]. 44-62 6 Claims ABSTRACT OF THE DISCLOSURE Motor fuel composition comprising a mixture of hydrocarbons in the gasoline boiling range containing (a) from 0.0004 to 0.1 weight percent based on said composition of an N-polyamine substituted alkenyl succinamic acid or corresponding succinimide in combination with (b) from 0.003 to 0.20 volume percent of (1) a polymer of a C to C unsaturated hydrocarbon, (2) a copolymer of a C to C unsaturated hydrocarbon, or (3) the corresponding hydrogenated polymer or copolymer, said polymer or copolymer having a molecular weight in the range from about 500 to 3500 and a method for operating an internal combustion gasoline engine.

BACKGROUND OF THE INVENTION Field of invention Internal combustion engines, particularly of the overhead valve design, are subject to a substantial build-up of hard, tenacious deposits on the intake valves and ports of the engine. These deposits seriously interfere with the operation of the engine. As the deposits level grows, the engine exhibits loss of power, rough idling, and, occasionally, valve burning. When the deposits become excessive, portions break off and are drawn into the combustion chamber. Instances of mechanical damage to the piston and piston rings caused by these deposits have been observed.

Considerable work has been conducted to determine the nature and cause of the intake valve deposits. The deposits themselves are composed essentially of the byproducts of fuel combustion and lubricating oil deterioration. Analysis of the deposits indicates that the viscosity index improvers contained in the lubricating oil act as binders for the deposits. Polymethacrylate viscosity index improvers, as an example, are one class of materials which appear to contribute materially to the deposits build-up.

An understanding of engine operation will show how lubricating oil deterioration can contribute to deposits in the fuel intake system. A spark-ignited internal combustion engine contains a reservoir of lubricating oil in the crankcase. When the engine is in operation, the primary lubrication is effected by the crankcase oil being splashed up on the operating parts of the engine and on the cylinder walls. A portion of this oil, however, is pumped under pressure to the upper parts of the engine to lubricate the Working parts therein. In an overhead valve engine, a small stream of the oil pumped to the upper section of the engine is constantly run down the intake and exhaust valve stems to insure that they are constantly lubricated in their guides during operation. The oil trickling down the intake valve stem, the valve head and around the intake port is apparently pyrolyzed under the temperatures prevailing, thereby contributing to the formation and build-up of the above-noted deposits.

This deposit problem is not encountered to any material extent in or around the exhaust ports or valves. This is believed to be due to the high temperatures existing at the exhaust valve during the exhaust cycle and to the action of the expelled exhaust gases which do not permit a lay- 3,676,089 Patented July 11, 1972 down of deposits or continually burns and carries off any potential deposits. However, this invention surprisingly has caused a substantial and unexpected increase in exhaust valve life for reasons not fully understood.

DESCRIPTION OF THE PRIOR ART AND RELATED COPENDING APPLICATION US. 3,131,150 discloses a class of reaction products of N-substituted alkenyl succinimides and polyamines for use in a lubricating oil composition. The reaction products are prepared by reacting an alkenyl succinic anhydride in which the alkenyl radical contains from 30 to about 200 carbon atoms with about an equal molar proportion of a polyamine from the group consisting of tetraethylene pentamine and dimethylaminopropylamine. These reaction products are metal free or ashless detergents for lubricating oil compositions and are effective for dispersing the precursors of deposits within the oil itself thereby inhibiting deposits formation on the engine parts.

US. 3,172,892 discloses the reaction product of high molecular weight succinic acids and succinic anhydride with an ethylene polyamine for use in a lubricating oil composition. Specifically, a hydrocarbon substituted succinic acid or succinic anhydride in which the substituted hydrocarbon radical is a large, substantially aliphatic hydrocarbon radical having at least about 50 carbon atoms is reacted with at least about one-half equivalent of an ethylene amine and heated to effect acylation and removal of water formed thereby. These reaction products are effective as sludge dispersants in crankcase lubricating oil temperatures for internal combustion engines.

A copending patent application, now US. 3,502,451 discloses a motor fuel composition for a gasoline internal combustion engine containing a polymer, copolymer or hydrogenated polymer. Specifically, a polymer of a C to C unsaturated hydrocarbon, a copolymer of a C to C unsaturated hydrocarbon, or a hydrogenated polymer or copolymer of a C to C unsaturated hydrocarbon having a molecular weight in the range from about 500' to 3500 is employed at a concentration from about 0.01 to 0.20 volume percent in the motor fuel composition for a sparkignited internal combustion engine. This motor fuel composition is effective for preventing or inhibiting the formation of deposits on the intake valves and parts of the engine.

SUMMARY OF THE INVENTION The fuel composition of the inventor comprises a mixture of hydrocarbons in the gasoline boiling range containing minor amounts of an additive combination of an N-polyamine-substituted alkenyl succinamic acid or corresponding succinimide with a. polymer, copolymer or hydrogenated polymer or copolymer of a C to C unsaturated hydrocarbon. More specifically, the fuel composition of the invention contains from about 0.0004 to 0.1 weight percent based on said composition of an N- polyamine-substituted alkenyl succinarnic acid or succinimide, prepared by reacting an alkenyl succinic acid or anhydride having the structural unit:

in which R is a hydrocarbon radical having a molecular weight from about 400 to about 3000 with from one-half to two equivalent amounts of a polyamine having the formula:

in which it is an integer and R is hydrogen or a low molecular weight alkyl radical, and from about 0.003 to 0.20 volume percent of (1) a homopolymer of a C to C unsaturated hydrocarbon, (2) a copolymer of C to C unsaturated hydrocarbons, or (3) the corresponding hydrogenated polymer or copolymer, said polymer, copolymer or hydrogenated derivative having a molecular weight in the range from about 500 to 3500. The method of the invention comprises supplying to and burning in a spark-ignited internal combustion gasoline engine the above-described motor fuel composition.

The discovery of an improved motor fuel composition from the combination of an EN-polyam-inesubstituted alkenyl succinamic acid or corresponding succinimide with a polymer, copolymer or hydrogenated polymer or copolymer of a C to C unsaturated hydrocarbon having a molecular weight from about 500 to 3500' was most surprising and unexpected. The reason for this is that an N- polyamine-substituted al-kenyl succinamic acid or corresponding succinirnide in a motor fuel composition has essentially no effect on the prevention of intake valve and port deposits in a spark-ignited internal combustion engine.

As more fully described in the above-noted patents, the N-polyamine-substituted alkenyl succinamic acid or succinimide is prepared by reacting an alkenyl succinic acid or anhydride having the structural unit:

in which R is a hydrocarbon radical having a molecular weight from about 400 to about 3000 with from one-half to two equivalent amounts of a polyamine having the formula:

in which x is an integer and R is hydrogen or a low molecular weight alkyl radical. R radical in the above formula is a hydrocarbon radical preferably derived from an olefin containing from 2 to 5 carbon atoms. Suitable olefins from which R is derived are ethylene, propylene, l-butene, 2-butene, isobutylene and the amylenes. The R radical generally has a molecular weight ranging from about 400 to 3000, corresponding to approximately 30 to 200 carbon atoms, with the preferred molecular weight being from 800 to 1200.

The R radical in the polyamine is hydrogen or a low molecular Weight alkyl radical having from 1 to 3 carbon atoms. x is an integer from 1 to about 6 and preferably from 2 to 4. Suitable polyamines and polyalkylene polyamines represented by the formula are ethylene diamine, propylene diamine, butylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, dipropylene triamine, tripropylene tetramine. Dialkylaminoalkylene amines, such as dimethyl aminomethylamine, dimethylaminopropylamine, diethylaminopropylamine and the like are also included.

From one-half to two equivalents of the polyamine are reacted with the alkenyl succinic acid or anhydride to form the reaction product. Equivalency of the polyamine reactant is based on the nitrogen content, ethylene diamine having two equivalents per mole. It is preferred to react approximately one equivalent of the alkenyl succinic acid or anhydride with about one equivalent of the polyamine.

In a typical preparation, a polyisobutylene succinic anhydride is prepared by the reaction of one mole of a polybutene having a molecular weight of about 1000 with 196 grams (2 moles) of maleic anhydride at 200 C. for 24 hours. The reaction mixture is cooled and 750 ml. hexane added. The solution is filtered to remove solid contaminants and then stripped under full vacuum to remove the hexane. The temperature is raised to about 200 C. to remove all traces of the excess maleic anhydride.

To a mixture of 1100 grams (1 mole) of the polyisobutenyl succinic anhydride and 400 ml. toluene there is added slowly at room temperature 52 grams (0.5 mole) 4 diethylene triamine. The mixture is heated and the watertoluene azeotrope is collected in a Dean-Stark trap. The reaction is complete when no more water is collected. The mixture is then heated to C. at reduced pressure to remove the toluene and yield a product consisting mainly of the bispolyisobutenyl succinimide.

In another typical preparation, a polyisobutylene succinic anhydride is prepared by the reaction of one mole of a polybutene having a molecular weight of about 1300 with 196 grams (2 moles) of maleic anhydride at 200 C. for 24 hours. The reaction mixture is cooled and 750 ml. of hexane added. The solution is filtered to remove solid contaminants and then stripped under full vacuum to remove the hexane. The temperature is then raised to about 200 C. to remove all traces of the excess maleic anhydride.

To a mixture of 1 mole of the polyisobutenyl succinic anhydride and 400 ml. of toluene there is added slowly at room temperature 0.5 mole of ethylene diamine. The mixture is heated and the water-toluene azeotrope is collected in a Dean-Stark trap. The reaction is complete when no more water is collected. The mixture is then heated to about 100 C. at reduced pressure to remove the toluene and yield a product consisting mainly of the bis-polyisobutenyl succinimide.

The polymer which is employed in the motor fuel of the invention is a polymer prepared from an unsaturated hydrocarbon, i.e. a monoolefin, diolefin or copolymer of either having an average molecular weight in the range of about 500 to 3500. Mixtures of olefin polymers with an average molecular weight falling within the foregoing range are also efi'ective. Olefins which can be employed to prepare the polyolefin polymers include ethylene, propylene, l-butene, Z-butene, isobutylene, amylene, hexylene, butadiene and isoprene. In general, the olefin monomers from which the polyolefins are prepared are unsaturated hydrocarbons having from two to six carbon atoms. The polyolefin polymers from C and C olefins, such as propylene and isobutylene, are particularly preferred for the practice of this invention. Other polyolefins which can be employed are those prepared by cracking polyolefin polymers or copolymers of high molecular weight to a polymer in the above-noted molecular weight range. Derivatives of the noted polymers obtained by saturating the polymers by hydrogenation are also eifective and are a part of this invention. The word polymers is intended to include the polyolefin homopolymers and copolymers and their corresponding hydrogenated derivatives.

The molecular weight of the polymer or polymer derivative component is important in preparing an effective fuel composition according to this invention. Effective fuel compositions of the invention require a polymer or hydrogenated polymer derivative having an average molecular weight in the range of 500 to 3500 as determined by an osmometer method. Highly eifective fuel compositions are obtained with polymers and derivatives having molecular weights in the preferred range from 650 to 2600. Very effective fuel compositions can be prepared from relatively low molecular weight polymers, that is using polymers having molecular weights in the range of 650 to 995.

The method of preparation of the olefin homopolymer, copolymers, hydrogenated polymers or copolymers is well known in the art and is not part of the present invention. The average molecular weight determination for the polymers is determined by the ASTM Osmometer Method identified as ASTM D2503-67. Examples of polymers which are etfective in the fuel composition of the invention together with their average molecular weight are as follows: polypropylene "800, polypropylene 975, polypropylene 1120, polypropylene 1150, polypropylene 1370, polypropylene 2560, polybutene-l 800, polybutenel 1200, polyisobutylene 850, polyisobutylene 1000, polyisobutylene 1200, polyisobutylene 1575, hy-

drogenated polybutene 1100, ethylene-butylene copolymer 810.

The method for preparing the N-polyamine-substituted alkenyl succinamic acid or succinimide is also well known as shown by the patents noted above. It is to be noted that suitable N-polyamine-substituted alkenyl succinamic acid or succinimides or mixtures containing same are commercially available. It is convenient to employ the reaction product dissolved in a mineral oil carrier.

The base fuel of the invention comprises a mixture of hydrocarbons boiling in the gasoline boiling range. This base fuel may consist of straight chain or branched chain parafiins, cycloparafiins, olefins and aromatic hydrocarbons or any mixture of these. This fuel can be derived from straight run naphtha, polymer gasoline, natural gasoline or from catalytically cracked or thermally cracked hydrocarbons and catalytically reformed stocks and boils in the range from about 90 to 450 F. The composition of the base fuel is not critical nor does the octane level of the base fuel have any material effect on the invention. Any conventional motor fuel base may be employed in the practice of this invention.

The fuel composition of the invention may contain any of the additives normally employed in a motor fuel. For example, the base fuel may be blended with an antiknock compound, such as a tetraalkyl lead compound, including tetraethyl lead, tetramethyl lead, tetrabutyl lead and mixtures thereof generally in a concentration from about 0.5 to 4.0 cc. per gallon of gasoline. The tetraethyl lead mixture commercially available for automotive use contains an ethylene chloride-ethylene bromide mixture as a scavenger for removing lead from the combustion chamber in the form of a volatile lead halide. The motor fuel composition may also contain any of the conventional anti-icing additives, corosion inhibitors. dyes, and the like as illustrated by US. 2,632,695; 2,844,449; 3,325,260; 3,232,724; 2,622,018 and 2,922,708.

The novel fuel composition of this invention is prepared by mixing suitable amounts of the prescribed N-polyamine-substituted alkenyl succinamic acid or succinimide and polymer additives to the base gasoline. The additives are readily soluble and may be added in any manner or order.

The test employed for testing the fuel compositions was the Buick Induction System Deposits Test conducted using a 1964 Buick 425 CID V-8 engine. The fuels employed in the tests were evaluated basis deposit ratings of the intake valves and ports of the engine as more fully described below.

The test is conducted using the noted engine equipped with a PCV (Positive Crankcase Ventilation) valve and installed on a dynamometer test stand with supporting equipment to control speed, load and engine temperatures. This test requires approximately 350 gallons of fuel and 4 gallons of lubricant per run.

Prior to each run, the cylinder heads are completely reconditioned and new intake valves installed. Special care must be taken to insure that the inlet valve-to-valve guide clearance be maintained between 0.0035 and 0.0045 inch. In addition, the valve seat widths are maintained between and inch. The engine block is completely overhauled in accordance with the procedures stated in the 1964 Buick Service Manual when blow-by or oil consumption become excessive.

The engine is charged with four quarts of oil and flushed for 15 minutes at 1500 r.p.m. Following an oil drain, four quarts of new oil are added and the fuel tests begun. The engine is operated on a four-stage six-hour cycle for a total of 16 cycles or 96 hours as follows:

B Typical values, not controlled. b Approximate valuesspark advance set 6 BTDC at 600 r.p.m.

Upon completion of a run, the cylinder heads and valves are removed and the valves visu'ally rated for the extent of deposit build-up on the valve tulip surface. The intake valve deposits are rated according to a merit rating scale running from 10 to 1. A rating of 10 indicates a perfectly clean valve while the rating of 1 is applied to an extremely heavily coated valve. Deposits around the port opening are rated Ttrace, L-light, M-medium and H-heavy.

The following examples illustrate the practice of this invention.

The base fuel employed was a typical premium grade gasoline containing about 3 cc. of tetraethyllead per gallon. This base fuel consisted of 25 percent aromatic, 20 percent olefinic and 55 percent aliphatic hydrocarbons as determined by FIA analysis. This gasoline had an ASTM distillation IBP of 87 R, an EJP. of 376 F. and a Research Octane Number of about 100. Except where otherwise noted, this base fuel contained 0.5 volume percent of a commercial corrosion inhibitor-mineral oil additive mixture. This additive mixture has no significant effect on the test for intake valve and port deposits.

A typical commercial gasoline without the additive of the invention gives an intake valve rating of about 6.0 and a port rating of heavy. An improvement in the valve rating of 0.5 unit above the base fuel and an acceptable port rating, Trace or Light, is a significant improvement. An improvement of 1.0 unit or more generally to 7.0 or above and a passing port rating is a very substantial improvement in engine cleanliness.

TABLE I.BUICK INDUCTION SYSTEM DEPOSITS TEST Fuel composition and additive concentration (1) Base fuel (2) Base fuel plus 0.013 wt. percent of the succinimide reaction product of 1 mole polyisobutenyl-lOOO-succinlc anhydride and 0.5 mole dlethylene triamine.

(3) Base fuel plus 0.1 vol. percent polypropene 800.

(4) Base fuel plus 0.05 vol. percent polypropene 800.

(5) Base fuel plus 0.075 vol. percent polypropene 800.

(6) Base fuel plus 0.075 vol. percent polypropene 800 plus 0.013 wt. percent of the succinimide reaction product of 1 mole polylsobntenyl-lGOO-succinic anhydride and 0.5 mole diethylene trlamlne.

7) Base fuel plus 0.043 vol. percent polypropene 800 plus 0.013 wt. percent of the succlnimide reaction product of 1 mole polyisobutenyl-lOOO-sueeinic anhydride and 0.5 mole diethylene triamlne.

1 Contained no corrosion inhibited-mineral oil additive.

Examples 6 and 7 are representative of the present invention and show surprisingly enhanced cleanliness of the engine intake valves and ports brought about by the unexpected cooperation of the additive combination of the invention in this test.

Obviously, many modifications and variations of the invention, as hercinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A motor fuel composition comprising (A) a hydrocarbon base fuel consisting of a mixture of hydrocarbons in the gasoline boiling range, (B) from 0.0004 to 0.1

Port rating Valve rating 5.8 MtOH. 5.7

Hours on test 7 weight percent based on said composition of an N-polyamine-substituted succinimide prepared by reacting an alkenyl succinic acid or anhydride having the structural unit:

R-OHCO- CHzOO- in which R is a hydrocarbon radical having a molecular weight from about 8 to 1200 with from one-half to two equivalent amounts of diethylene triamine and (C) from 0.003 to 0.20 volume percent of (1) a homopolymer of a C to C unsaturated hydrocarbon, (2) a copolymer of C to C unsaturated hydrocarbons or (3) the corresponding hydrogenated polymer or copolymer, said polymer, copolymer or hydrogenated derivative having a molecular weight in the range from about 500 to 3500.

2. A motor fuel composition according to claim 1 in which said N-polyamine-substituted alkenyl succinimide is the reaction product of polybutene-lOOO-succinic anhydride and diethylene triamine.

3. A motor fuel composition according to claim 1 in which said polymer of an unsaturated hydrocarbon is polypropene 800.

4. A method for preventing the build-up of intake valve and port deposits in a spark-ignited, internal combustion gasoline engine which comprises supplying to and burning in said engine a motor fuel composition comprising (A) a hydrocarbon base fuel consisting of a mixture of hydrocarbons in the gasoline boiling range, (B) from 0.0004 to 0.1 Weight percent based on said composition of an N-polyamine-substituted succinimide prepared by reacting an alkenyl succinic acid or anhydride having the structural unit:

in which R is a hydrocarbon radical having a molecular weight from about 800 to 1200 with from one-half to two equivalent amounts of diethylene triamine and (C) from 0.003 to 0.20 volume percent of (1) a homopolymer of a C to C unsaturated hydrocarbon, (2) a copolymer of C to C unsaturated hydrocarbons or (3) the corresponding hydrogenated polymer or copolymer, said polymer, copolymer or hydrogenated derivative having a molecular weight in the range from about 500 to 3500.

5. A method according to claim 4 in which said N-polyamine-substituted alkenyl succinimide is the reaction product of polybutene-MOO-succinimide and diethylene triamine.

6. A method according to claim 4 in which said polymer of an unsaturated hydrocarbon is polypropene 800.

References Cited UNITED STATES PATENTS 3,223,495 12/ 1965 'Calvino et a1 44-71 3,280,033 10/1966 Drummond 4471 X 3,307,928 3/1967 Chaikivsky et al 4463 3,401,118 9/1968 Benoit 44-63 X 3,443,918 5/ 1969 Kautsky et al 44-63 3,502,451 3/ 1970 Moore et al 44-58 DANIEL E. WYMAN, Primary Examiner W. I. SHINE, Assistant Examiner 

